318 Cam

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MOPARJ

MOPARJ

What can I upgrade now?
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This is somewhat related to an earlier post about getting 275 horses for a 318. If i have a Comp260 cam in my 318 with manifolds, can i expect an appreciablr gain if i switch up to a Comp XE268? If so, about how much?

Also, would 245-265 horsepower sound like a good estimate for my current combo: 88,000 mile 318 w/ A/C, Edelbrock 600cfm, Performer intake, double roller chain, Comp lifters and springs, new valve seals, comp 260 cam, manifolds, flowmaster 2.5" dual exhaust.

Also, can my stock converter hold up and perform well with the current cam or a XE268?
 
Maybe i have too many questions at one time, so i should just ask one. Does 245-260 horsepower sound like a good estimate out of the current combo i have listed in the previous thread?
 
I think more like 200 HP, due to the a/c and the manifolds. A stock 318 only had 150 HP. The only thing thats going to increase the HP is the intake ,mufflers, and the carb. The cam wont have much effect due to the exhaust manifolds. Now if you put hedders on it, and drop the a/c as this hurts the power more than anything, they will help pick up the extra HP.
 
On a stock 318, the 260 will be a happier combo. The 268 really likes more then 9.0:1 compression. So I would say no, you won't gain anything, and may in fact lose some of your low end. The 268 really likes a bit more stall speed in the converter as well. In any event keep a split-pattern cam, the added exhaust duration will help with your system.

As for the a/c, the compressor is nothing more than an idler pulley with the system in the OFF mode. For maximum performance, turn the a/c off.
 
BJR Racing said:
I think more like 200 HP, due to the a/c and the manifolds. A stock 318 only had 150 HP. The only thing thats going to increase the HP is the intake ,mufflers, and the carb. The cam wont have much effect due to the exhaust manifolds. Now if you put hedders on it, and drop the a/c as this hurts the power more than anything, they will help pick up the extra HP.
Click to expand...


Doesn't horsepower stock depend on the year of the 318? I was told by an outside source that my stock 318 put out about 175HP.
 
well, the motor does have an edelbrock 4 barrel 600 carb, performer intake, stock manifolds, dual 2.5" flowmaster exhaust, double roller chain, so it has more than just the cam. the a/c has some kind of an issue, so its never on. Does this sound a bit better in making closer to 240 or so? It has run a best of 15.5 with the stock 2.76 7.25 rear, so im happy for a mild street cruiser. tell me what you all think. Thanks.
 
Gross horsepower was just that, the total amount of horsepower the engine made when the factory rated it. SAE net horsepower is a uniform standard which simulates the engine as installed. That means with the air filter on, fan belt on turning the water pump and alternator, and the complete vehicle exhaust system. Also the measurements are taken at or corrected to a "Standard Day" (15 degrees C, seal level, and 29.92" Hg). Before 1972, manufacturers could pretty much rate an engine at whatever they wanted to.

If you are running a 15 second quarter with 2.76 gears, I would WAG about 250 hp as is, not knowing your actual weight. If it were me, I would go looking for some 3.23 or 3.55 gears about next. That should be some pretty good bang for your buck.
 
I dont know how big you are, and I'm guessing MPH around 90(?) but you should be around 230/240 at the crank now.
 
lol. yeah...im 5' 11", about 165 lbs. It has mph around 90.5, actually, because of the gearing. I kinda thought around 24o at the crank, which i feel is acceptable for what it is. I may add 9:0:1 pistons when its rebuilt in a year or two.
 
If your car is 3200 and you are 165 for a total weight of 3365 lbs. the the 90 MPH speed only yeilds 201.9 HP. This is close to what I stated in the 3rd post. The gross at the flywheel then comes to 242 HP. Which is what you were looking for, and a 318 should already be at 9.0:1 for pistons.
 
Wait a minute, I have been reading and trying to learn as much as I can about this 318 build and ask questions when I see it is relevent to my situation and now is one of the those times, see 318 horsepower thread for my situation if interested. I was lead to believe that a stock 318 only had maybe 8:1/8.5:1 compression. I jsut read that you said that it should be 9.0:1. My 318 is a 1987 and it had 302 heads on it.
 
1967-1972 318's were 9:0:1 compression, where as in 1973, it dropped to 8:5:1. Sometime down the line, in the mid 80's i believe, it dropped a tad more to 8:4:1.
 
I think your '87 with 302 heads will have somewhere around 8.3:1 if you take it apart and measure. Early ones are best. The others all just kind of blurr together in a low compression mess. Dont blieve the actual published figures. They are always between .2 and .5 lower. Always.
 
Here's some compression info.

Horsepower and torque figures prior to 1972 are SAE gross (measured without any accessories connected to the engine). Horsepower and torque figures from 1972 and after are SAE net (measured with all accessories connected to the engine). Not all engines were available with all cars — or even to the general public.

For more information, see allpar’s pages on the 273, 318, and 360 / 340 / 383 and 413 / 361

Engine Year(s)



Comp Ratio Horsepower Torque (lb-ft)

318-2 bbl 1960-1962 9.0 to 1 230 @ 4400 340 @ 2400
318-4 bbl 1960 9.0 to 1 255 @ 4400 345 @ 2800
318-4 bbl 1961-1962 9.0 to 1 260 @ 4400 345 @ 2800
318 1968-1969 9.2 to 1 230 @ 4400 340 @ 2400
318 1970 8.8 to 1 230 @ 4400 320 @ 2000
318 1971 8.6 to 1 230 @ 4400 320 @ 2000
318 1972 8.6 to 1 150 @ 4000 260 @ 1600
318 1973 8.6 to 1 150 @ 3600 265 @ 2000
318 1974 8.6 to 1 150 @ 4000 255 @ 2200
318 1975-1976 8.5 to 1 145 @ 4000 255 @ 1600
 
Okay so here is a question, I just found out that my 87 318 has a roller cam in it. Do I need to change the roller lifters, and push rods if I get a new roller cam? Or can I use the same ones?
 
You can re-use the lifters on hydraulic or solid roller cams. There is no break in on a roller cam.
 
there is no break in ??? Wow. so if you were going to suggest a roller cam what would it be? I plan on having a 2500 stall and doing the 302 heads with 360 exhaust valves and a good clean up job on the ports like everyone suggested. Basically leaving the lower end stock for now until she gets some seat time. then in the winter down time do the lower end and whatever else needs to be to hit the final goal of mid twelves.
 
So I was reading another thread and heard that the MP cams are not what they used to be and to look other places. Is that correct as I am still trying to figure out what cam to use in my 318 also. Since I have found out that it has a stock roller in it now I am really confused as to what is the best to use. Also I was thinking of going with timing gear set inset of chain set up. Is that a good idea or not? I just like the sound that you get from gears. Not sure if there is really any benefit from them or not. Any input from the masses of knowledge out there?
 
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